Dynamo-electric machine



B. E. HELlMUHD.

DYNAMO ELECTRIC MACHINE. APPLICATION FILED DEC. 14, was.

1,351,035. Patented Aug. 31; 1920.-

Trolley m i Mp/ are a I AH F/ 1 APG 4 R/ MP2 WITNESSES: INVENTOR lf 5He//mu/2 W g 0 WW ATTORNl EY UNITED STATES PATENT OFFICE.

RUDOLF E. HELLMUND, 0F PITTSBURGH, PENNSYLVANIA, ASSIGNOR TO WESTING-HOUSE ELECTBIC AND MANUFACTURING COMPANY, A CORPORATION OF PENNSYL-VANIA.

DYNAMIC-ELECTRIC MACHINE.

Application filed December 14, 1915.

To all whom it may concern:

Be it known that I,RUnoLF E. HELLMUND, a subject of the Emperor ofGermany, and a resident of Pittsburgh, in the county of 'kllegheny andState of Pennsylvania, have invented a new and useful Improvement inDynamo-Electric Machines, of which the following is a specification.

My invention relates to dynamo-electric machines and systems of controltherefor and especially to machines of the-dynamotor type.

One object of my invention is to provide a achine of the alove-indicated character which shall be relatively simple and inexpensivein construction and effective and reliable in operation, and which shallembody means for effecting a variation of the voltage ratio between thetwo commutator cylinders, or the equivalent, of the machine underprcdeterminml conditions, either by simultaneously increasing thevoltage of one cylinder and decreasing the voltage of the other or bymaintaining the voltage of one cylinder substantially constant andvarying the voltage of the other cylinder, as hereinafter more fully setforth.

More specifically stated, it is the object of my invention to provide adynamo-electric machine having a rotor provided with a plurality ofcommutator cylinders, a stator frame having a plurality of wound mainand auxiliary polar projections, and a plurality of sets of brushesdisposed upon the respective cylinders in such manner that the voltagebetween brushes on one cylinder shall be proportional to the sum of themain and the auxiliary polar fluxes, and the voltage between brushes onthe second cylinder shall be proportional to the main flux.

A further object of my invention is to provide a system of controlembodying a machine having the above-indicated characteristics, whereby,under regenerative conditions of a plurality of parallel-related maindynamo-electric machines, the excita tion of the lield windings thereofmay be automatically varied oppositely to the variations of armature orload current, thus providing a stable regenerative system.

In connection with regenerative systems and in various other cases, itis often desirable to obtain from a relatively high supply-circuitvoltage a low excitation volt- Specification of Letters Patent.

Patented Aug. 31, 1920.

Serial No. 66,725.

age, and the well-known type of dynamotor is generally employed for suchpurposes. The dynamotor has various advantages over an equivalentmotor-generator set by reason of its lightness of weight and relativelylow cost, and also because it is, at times, desirable to have thesecondary voltage, that is, the lower voltage, of the dynamotor respondrapidly to any change in the primary voltage. The desired rapidity ispossible only when the field fluxes that induce the primary and thesecondary voltages are identical, as is the case in a dynamotor.However, the standard dynamotor has the disadvantage that it does notpermit of a change of the ratio of its high and low voltages. In someinstances, it may be desirable to provide a rising-voltagecharacteristic in the output or low-voltage circuit of the dynamotorand, in other cases, to supply a constant-voltage characteristic.

According to my present invention, I provide a novel type of dynamotoror double comn'iutator machine for effecting, in one case, asimultaneous opposite variation of the high and low "oltages of themachine, under predetermined conditions; or, in accordance with anothermodification, the voltage of the motor or high-voltage commutatorcylinder is maintained substantially constant while the voltage of thegenerator or low-voltage commutator winding is automatically varied inthe desired 'manner.

The standard type of dynamotor employs a plurality of main polarprojections and a plurality of comm utating polar projections, the setsof brushes on the respective com mutator cylinders being disposed inalinement with the commutating polar fluxes, in accordance with familiarpractice. In accordance with certain features of my present invention, Iso dispose the main polar projections and a plurality of auxiliary orsecondary polar projections that certain of their respective axes arelocated intermediate spaced pairs of non-corrcsponding brushes; that is,the brushes on the different cylinders.

In the accompanying drawing, Figure l is a diagrammatic view of adynamo-electric machine constructed and connected in ac cordance with myinvention, the machine being shown in end elevation; and Fig. 2 is adiagrammatic view, in side elevation on a smaller scale and with partsbroken away, of the machine shown in Fig. 1.

Referring to Fig. 1 of the drawing, the system shown comprises aplurality oi? suit able supply-circuit conductors respectively markedTrolley and Ground, a variable translating device TD; and adynamoelectric machine D of the general dynamotor type.

The translating,- device TD may comprise a plurality of lamps orresistors or other devices which. may be connected in or cut out oicircuit, as may be desired, whereby a variable load may be introducedinto the circuit of the low-voltage armature winding of the dynamotor,as more fully set forth hereinafter.

The dynamotor D comprises a rotor R that is provided with a motor orhigh-voltage commutator cylinder M and a generator or low-voltagecommutator cylinder G that are preferably disposed at the respectiveends "of the rotor and are connected in the usual manner, to a plurality01"" separate armature windings that are here diagrammatically shown atANY 1 and AVV2 in Fig. 2. A stator frame SP2 is provided with aplurality of oppositely-disposed main polar projections MP1 and MP2, anda plurality of auxiliary polar projections or secondary projections APaSand APG that are disposed in non-quadrature relation to the mainprojections MP1 and MP2; and a plurality of suitable field-magnetwindings MFl and AFl are disposed upon the main projections and theauxiliary projections, re spectively.

The circuit of the shunt field winding M131 is established from theTrolley through a junction-point 10, the field winding MF1 and ajunction-point 11 to the negative supply-circuit conductor Ground. Thejunction-points 10 and 11 are also directly connected to the brushes 1and 2, respectively, of the motor commutator cylinder 'll/li.

The auxiliary field winding; A1 1 is connected in series-circuitrelation with the brushes 4 and 3 of the generator commutator cylinder Gand the variable translating device TD.

The motor commutator cylinder M is provided with a set of suitablebrushes 1 and 2, and the generator commutator cylinder Gr is alsoprovided with a set of brushes 3 and t. instead of the brushes beingalined with each other, the pairs of non-corresponding brushes areshifted with respect to each other and the main polar projections havetheir axis lying intermediate such spaced pairs. For example, in. thesystem shown, the axis of the main polar projections extend through apoint intermediate non-corresponding brushes 1 and 4 and a second pointintermediate the non-corresponding brushes 2 and 3. However, theauxiliary polar projections have their axis disposed in substantialalinement with the brushes 1 and 2 that are associated with the motorcommutator cylinder lri, and thus, the auxiliary polar projections makean angle with the corresponding: main polar projections that ismaterially less than 9*?) electrical degrees.

The main field winding Ml l is disposed around the main polarprojections MP1 and MP2 in such manner as to produce north and southpoles of magnetism therein, as indicated by the letters a and s,respectively. The circuit of the auxiliary field winding re -1E1 isdisposed upon the auxiliary polar projections A 5 and APtS to createnorth and south magnetic poles in accordance with the designations a ands, respectively.

It will be observed that, since the polar projections MP1 and APSprovide north magnetic poles, the flux threading the armature windingA31 1, that is associated with the motor commutator cylinder M, isproportional to the sum oi the main and auxiliary polar fluxes, whilethe iiux linking with the armature winding;- jiW2, which is associatedwith the commutator cylinder G is proportional to the main polar iiux byreason of the fact that the auxiliary polar flux passes parallel to thebrushes 3 and 4.

The advantages of the construction just described may be set forth asfollows: In other types of' dynamotors the primary armature winding,that is, the armature winding that is associated with the motorcommutator cylinder M, is not used to as good advantage as'possible,because the voltage induced between the motor commutator cylinderbrushes 1 and 2 is the diiierence be tween certain positive and negativevoltages that respectively correspond to the various field fluxes,thereby requiring the use 071 a relatively large number of conductors toproduce a certain total voltage. In the structure that is illustrated inF 1, however, the auxiliary polar projections AP and A1 6, by reason oftheir alinement with the brushes 1 and 2, serve as commutatine; polestherefor. @onsequently, the auxiliary polar projections exert no directeffect upon the voltage between the brushes 1 and 2 but serve toincrease the voltage between the other brushes 3 and 4 wlth an increasedload current in the translatmgdevice TD.

In this way, I provide a dynamotor 1n which the motor voltage ismaintained substantially constant, while the generator voltage is variedin accordance with predetermined'conditions to thus vary the voltageratio of the two commutator cylinders.

in Fig. 1, clockwise rotation was assumed, as indicated by the arrows,and the disposition of the main and auxiliary field windings withrespectto the sets of brushes was determined in accordance with such direction.If rotation in the counterclock-wise direction is assumed, in general,the polarity of the auxiliary polar projections must be reversed or therelative locations of the various sets of brushes must be interchanged.It is believed that the foregoing statement will be evident to thoseskilled in the art without requiring any further illustration ordescription.

It should be noted that, although I have shown and described a machinehaving two commutator cylinders, my invention is capable of widerapplication; and a machine having a single armature winding and a singlecommutator cylinder with a double set of brushes, or the equivalent, maybe utilized.

Moreover, if desired, field-magnet windings of the familiar distributedtype may be employed instead of the concentrated or polar field-magnetwindings that are illustrated, as will be understood.

I do not wish to be restricted to the specific circuit connections orstructural details and arrangement of parts herein set forth, as variousmodifications thereof may be made without departing from the spirit andscope of my invention. I desire, therefore, that only such limitationsshall be imposed as are indicated in the appended claims.

I claim as my invention:

1.. In a dynamo-electric machine, the combination with a rotor having aplurality of windings and commutators therefor, of a plurality of spacedsets of brushes for said commutators, and a stator frame having aplurality of main and auxiliary polar projections, the axes of all themain projections lying intermediate the commutating zones of spacedpairs of non-corresponding brushes and the axes of said auxiliaryprojections substantially coinciding with the commutating zone of oneset of said brushes.

2. In a dynamo-electric machine, the combination with a rotor having amotor and a generator winding and commutators therefor, of a pluralityof spaced sets of brushes for said commutators, a plurality of mainpolar projections having their axes lying intermediate the commutatingzones of a spaced pair of non-corresponding brushes, and a plurality ofauxiliary polar projections having their axes substantially coincidingwith the commutating zone of one set of said brushes and respectivelyintersecting the axes of the corresponding main polar projection at anangle materially less than ninety electrical degrees.

3. In a dynamo-electric machlne, the combination with a rotor having amotor and a generator winding and commutators therefor, of a pluralityof spaced sets of brushes for said commutators, and a stator framehaving a plurality of main polar projections having their axes lyingintermediate the commutating zones of spaced pairs of non-correspondingbrushes, and a plurality of auxiliary polar projections mechanically andelectrically related to said brushes in such manner as to perform thedouble function of aiding to vary the ratio of the volt ages appearingat said sets of brushes and to act as commutating polar projections forthe respective brushes on the motor commutator cylinder.

4. In a dynamo-electric machine,the combination with a rotor having ahigh-voltage and a low-voltage winding and a commutator for each ofthese windings, of a plurality of spaced sets of brushes for saidcommutators, a stator frame having a plurality of polar projections anda plurality of sets of field windings to excite said. projections andthe rotor, means whereby the excitation of one of the sets of fieldwindings is changed so as to increase the total voltage induced in thelow-voltage winding without substantially changing the total field fluxbetween the commutating coils of the high-voltage winding.

5. In a dynamo-electric machine,the combination with a rotor havingcoils located on a single core, and commutating means, of a plurality ofspaced sets of brushes for said commutatin means,one of said sets ofbrushes acting as a motor brush set, and another set acting as agenerator brush set, a stator core, a plurality of main polarprojections and a plurality of materially smaller auxiliary polarprojections, and a plurality of sets of field-magnet windings located onsaid projections and respectively load-current-excited and shuntexcited. only, said windings being mechanically and electrically relatedto said brushes in such a manner as to induce fluxes of the samepolarity only between the eonnnutating zones of one set of brushes and aflux from only the main projections between the commutating zone of theother set of brushes, whereby the excitation of only the auxiliary polesis inherently varied with the load of the machine.

In testimony whereof, I have hereunto subscribed my name this 10th dayof Dec., 1915.

RUDOLF E. HELLMUND.

